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The Nervous System. By: Kaylen Bunch & Kenzie Murphy. Major Structures. Central Nervous System (CNS): Brain & Spinal Cord Peripheral Nervous System (PNS): Network of nerves & Neural tissues Major Function: Sends signals threw the brain and spinal cord to the rest of the body. .

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the nervous system

The Nervous System

By: Kaylen Bunch & Kenzie Murphy

major structures
Major Structures
  • Central Nervous System (CNS):
    • Brain & Spinal Cord
  • Peripheral Nervous System (PNS):
    • Network of nerves & Neural tissues
  • Major Function:

Sends signals threw the brain and spinal cord to the rest of the body.

  • Specialized conductors of impulses that enable the body to interact with it\'s internal and external environments.
  • Neuroglia: supporting tissue
  • Axon: long slender projection of a nerve cell that conduct impulses away from the cell body.
  • Dendrites: Are short & unsheathed, & transmit impulses to the cell body.
  • Motor Neurons: Contractions in muscles & secretions from glands & organs.
  • Sensory Neurons: Attached to sensory receptors & transmit impulses to CNS.
  • Interneurons: Mediate impulses between sensory & motor neurons.
nerve fibers
Nerve Fibers
  • A single elongated process.
  • PNS fibers: Wrapped by sheaths containing Schwann cells, so damage is reversible,
  • CNS fibers: No Schwann cells, so permanent damage.
nerves a bundle of nerve fibers that connect to various parts of the body
Nerves: a bundle of nerve fibers that connect to various parts of the body
  • Afferent: Conducting to the CNS
  • Efferent: Conducting to muscles, organs, & glands.
  • Mixed: Mixture of afferent and efferent.
nerve impulse
Nerve Impulse
  • All or None Principle: No transmission occurs until the stimulus reaches a minimum strength then a maximum impulse is produced.
  • Synapse: A specialized knoblike branch ending.
  • Neurotransmitter: chemical agent helper.
cns central nervous system
CNS: Central Nervous System
  • Brain and Spinal Cord
    • Divided into white and gray matter.
    • Spinal Cord’s gray matter is in a “H” shape.
  • The nervous tissue consists of millions of nerve cells & fibers
  • Male- 1380g. or 3.04lbs.
  • Female- 1250g. or 2.75lbs.
  • Function:
    • Receives information from the body
    • Interprets it
    • Gives a response to it
    • Helps perform vital operations
brain meninges
Brain (Meninges)
  • 3 membranes that enclose the brain.
  • Meninges support blood vessels and contain cerebrospinal fluid.
  • Pia mater - inner layer
  • Arachnoid – middle layer
  • Dura mater – outer layer
  • Description: Divided by the longitudinal fissure into 2 cerebral hemispheres.
  • Function: Contains nerve centers that govern all sensory and motor activity.
  • They are joined by large fiber tracts that allow information to pass between them.



  • The surface of each hemisphere is arranged in folds creating bulges(convolution) & shallow furrows( sulcus).
  • Cerebral Cortex: The surface of each hemisphere, composed of gray, unmyelinated cell bodies.
    • Divided into lobes to identify certain locations.
cerebrum lobes
Cerebrum Lobes
  • Frontal: Major motor area, site for personality, & speech.
  • Parietal: Contains centers for sensory input from all parts of the body & is the site for the interpretation of language.
  • Temporal: Contains centers for hearing, smell, & language input.
  • Occipital: Primary sensory area for vision.
  • Occupies a place in the back of the skull, is oval shaped & divided into lobes by deep fissures. Is also connected to every part of the CNS.
  • Function: Coordination of voluntary & involuntary complex patterns of movement & adjusts muscles to automatically maintain posture.
  • Thalamus: Relay center for all sensory & motor impulses being transmitted to the sensory & motor areas.
  • Hypothalamus: Regulates autonomic nervous activity & contains neurosecretions used to control metabolic activities.
  • Contains centers that process visual, auditory, & sensory data & relay information to & from the cerebrum.
  • Midbrain: below cerebrum & above pons.
    • Contains 4 small masses of grey cells that are associated with visual reflexes & sense of hearing.
  • Pons: broad band of white matter
  • Contains fiber tracts linking the cerebellum & medulla to higher cortical areas.
  • Plays a role in somatic & visceral motor control.
  • Medulla Oblongata: Connects the pons & the rest of the brain to the spinal cord.
  • Acts as the cardiac, respiratory, & vasomotor control centers.
  • Controls
    • Breathing
    • Swallowing
    • Coughing
    • Sneezing
  • Vomiting
  • Heartbeat
  • Arterial blood pressure
spinal cord
Spinal Cord
  • Adult cord is about 44 cm. long.
  • Function:
    • Conduct sensory impulses to the brain
    • Conduct motor impulses from the brain
    • Reflex center for impulses entering & leaving spinal cord without involvement of the brain.
spinal cord1
Spinal Cord
  • Conus Medullaris: Between 12th thoracic & 1st lumbar vertebra. The cord becomes conically tapered.
  • Filum Terminale: terminal thread of fibrous tissue extends from the conus medullaris to 2nd sacral vertebra.
spinal cord2
Spinal Cord
  • Cauda Equina: (horses tail) terminal portion that forms the nerve fibers that are the lumbar, sacral, & coccygeal spinal nerves.
cerebrospinal fluid
Cerebrospinal Fluid
  • Colorless fluid produced by the choroid plexuses within the ventricles of the brain.
  • Circulates through the ventricles, central canal, & subarachnoid space. Is removed by the arachnoid villi.
  • Adult 120 – 150mL.
  • Cushions the brain & spinal cord from shocks that could cause injury.
pns peripheral nervous system
PNS: Peripheral Nervous System




  • Network of nerves branching throughout the body from the brain & spinal cord.
  • 12 pairs of cranial nerves attach to the brain.
  • 31 pairs of spinal nerves connected to the spinal cord.




cranial nerves
Cranial Nerves
  • Attached to the brain. Arranged symmetrically, 12 to each side of the brain.
  • Function: Provide sensory input, motor control, or a combination of these functions.
spinal nerves
Spinal Nerves
  • 31 pairs along the length of the spinal cord & from the vertebral canal.
  • Each nerve is divided into 2 roots.
  • Dorsal/Sensory roots: composed of afferent fibers carrying impulses to the cord
  • Ventral Roots: contain motor fibers carrying efferent impulses to muscles & organs
spinal nerves1
Spinal Nerves
  • Cervical: 8 pairs
  • Thoracic: 12 pairs
  • Lumbar: 5 pairs
  • Sacral: 5 pairs
  • Coccygeal: 1 pair
ans autonomic nervous system
ANS: Autonomic Nervous System
  • A part of the PNS.
  • Controls involuntary bodily functions:
    • Sweating
    • Secretion of glands
    • Heart
    • Arterial blood pressure
    • Smooth muscle tissue
ans autonomic nervous system1
ANS: Autonomic Nervous System
  • Composed of efferent fibers from certain cranial & spinal nerves that are divided into the:
    • Sympathetic Division
    • Parasympathetic Division
  • The 2 divisions counteract each other to keep the body in a state of homeostasis.
sympathetic division
Sympathetic Division
  • Since sympathetic fibers synapse with cell bodies in the sympathetic ganglia, they produce widespread innervation when activated.
  • This is called the fight-or-flight response.
  • This division also causes the release of epinephrine (adrenaline), causing an adrenaline rush.
fight or flight response
Fight-or-Flight Response
  • During this a person experiences:
parasympathetic division
Parasympathetic Division
  • Works to conserve energy and innervate the digestive system.
  • When activated it:
    • Stimulates salivary & digestive gland
    • Decreases metabolic rate
    • Slows heart rate
    • Reduces blood pressure
    • Allows material through intestines & absorption of nutrients by blood
alzheimer s disease ad
Alzheimer’s Disease (AD)
  • Loss of memory & other cognitive functions.
  • Involves the parts of the brain that control thought, memory,& language.
  • Begins after age 60, and risk goes up with age.
  • Not a normal part of aging.
  • Inflammation of the brain
  • Many types are caused by viral infection
  • Symptoms:
    • Sudden fever
    • Vomiting
    • Stiff neck & back
    • Clumsiness
  • Mild cases have full recovery
  • Severe cases can cause death
  • Acute phase last 1 to 2 weeks
  • Infection of the membranes that surround brain & spinal cord.
  • Symptoms:
    • High fever
    • Vomiting
    • Difficulty waking up
  • Caused by many different viruses & bacteria.
  • Viral cases are 10 days or less.
  • Can be deadly if not treated promptly.
  • Brain disorder involving repeated seizures of any type.
  • Cluster of nerve cells in the brain signal abnormally.
  • Symptoms: Begin during childhood
    • Strange sensations.
    • Muscle spasms.
    • Loss of consciousness.
epilepsy seizure classification
Epilepsy: Seizure Classification
  • Partial seizure: Electrical disturbances are in the brain near the source.
  • Generalized: No onset that involve both hemispheres of the brain.
  • Unilateral: Electrical discharge in only one hemisphere.
  • Unclassified: Doesn’t fit in other categories.
multiple sclerosis ms
Multiple Sclerosis (MS)
  • A chronic, debilitating disease that attacks the CNS.
  • Causes the body to send antibodies & white blood cells against proteins in the myelin sheath.
  • Causes inflammation & injury to the sheath.
  • Damage slows muscle coordination, visual sensation, & other nerve signals.
  • Varies in severity.
multiple sclerosis ms1
Multiple Sclerosis (MS)
  • Symptoms:
    • Paralysis.
    • Uncontrollable spasms.
    • Numbness & tingling.
  • Genetic link to the disease.
  • Estimated 400,000 Americans suffer it.
  • Occurs between ages 20 & 50.
  • No known cure.
parkinson s disease
Parkinson’s Disease
  • Degeneration of nerve cells in the part of the brain that controls movement and causes a shortage of dopamine.
  • 1st Symptom is tremor of a limb.
  • Symptoms:
    • Inability to move.
    • Stooped posture.
    • Speak in a soft voice.
parkinson s disease1
Parkinson’s Disease
  • Causes:
    • Depression.
    • Dementia.
    • Sleep disturbances.
  • More common in men than women.
  • Average age of onset is 60.
  • No cure.
stroke brain attack
Stroke (Brain Attack)
  • Death of brain tissue when it doesn\'t get enough blood & oxygen.
  • Caused either by bleeding or blood clots in the brain.
  • 3rd leading cause of death in the U.S.
  • Occurs in men more often than women.
the ear
The Ear
  • Site of hearing & equilibrium.
  • External: The appendage on the side of the head.
  • Contains:
    • Auricle (Pinna)
    • External acoustic meatus (Auditory canal)
    • Tympanic membrane (Eardrum)
  • Many glands line the canal & secrete earwax to lubricate & protect the ear.
the ear1
The Ear
  • Middle: A tiny cavity in the temporal bone of the skull.
  • Contains:
    • Ossicles: Malleus, Incus, & Stapes.
  • Lined by mucous membrane.
  • Functions:
    • Transmits sound vibrations.
    • Equalizes external/internal air pressure.
    • Controls potentially damaging or disruptive loud sounds.
the ear2
The Ear
  • Inner: Consists of a membranous labyrinth (mazelike network).
  • Contains:
    • Cochlea.
    • Vestibule.
    • Semicircular canals.
hearing loss
Hearing Loss
  • Noises over 85 decibels can cause permanent loss.
  • 2 in every 10 teens have lost some of their hearing.
  • As it progresses you will start having difficulty hearing when there is noise in the background.
things that cause hearing loss
Things that cause Hearing Loss
  • Sensory Overload
  • Old age
  • Undiagnosed tumors or undertreated infections
  • Non-functioning ear canal or bones
  • Damage from drugs, trauma, or pressure
meniere s disease
Meniere’s Disease
  • Abnormality of the inner ear
  • Symptoms:
    • Vertigo
    • Tinnitus
    • Fluctuating hearing loss
  • Affects only one ear
  • No cure
otitis media om
Otitis Media (OM)
  • Otitis: inflammation of any part of the ear.
  • OM is the most common type.
  • Begins when viral or bacterial infections of the throat spread to the middle ear.
  • More common in children than adults.
  • 75% of children have at least one episode of OM by their 3rd birthday.
common signs of om
Common Signs of OM
  • Unusual irritability
  • Difficulty sleeping
  • Tugging at one or both ears
  • Fever
  • Fluid draining from the ear
  • Loss of balance
  • Unresponsive to quiet sounds
  • Sensation of ringing or roaring sounds in both ears.
  • At least 12 million Americans suffer this.
  • Causes:
    • Hearing loss
    • Loud noise
    • Medicine
    • Other health problems
  • No cure.
  • Treatments that give some relief:
    • Hearing aids
    • Maskers
    • Medicine or drug therapy
the eye
The Eye
  • Function: vision & sight
  • Orbit: Cone-shaped cavity in the front of the skull. Holds the eyeball.
  • Muscles of the Eye: 6 short muscles that provide support & rotary movement of the eyeball.
  • Eyelids: Protect the eyeballs from intense light, foreign particles, & impact.
the eye1
The Eye
  • Conjunctiva: A protective covering for the exposed surface of the eyeball
    • Helps keep the eyelid & eyeball moist.
  • Lacrimal Apparatus: Produces, stores,& removes tears that cleanse & lubricate the eye.
  • Function: Organ of vision
  • Sclera: outer white part of the eye.
  • Cornea: Transparent anterior portion of the eyeball.
    • Bends light rays & helps focus them on the retina.
  • Choroid: Pigmented vascular membrane that prevents internal reflection of light.
  • Ciliary Body: A thickened potion of the vascular membrane.
    • Secretes nutrient fluids that nourish the cornea, lens, & surrounding tissue.
  • Iris: colored membrane of the eyeball.
  • Retina: Innermost layer of the eye.
  • Lens: sharpens the focus of light on the retina.
  • Clouding of the eye’s lens.
  • Doesn’t spread from one eye to the other, but can be in both.
  • Symptoms:
    • Cloudy or blurry vision
    • Poor night vision
    • Double or multiple vision
    • Often need for change in eyeglasses
conjunctivitis pinkeye
Conjunctivitis (Pinkeye)
  • An inflammation of the conjunctiva.
  • The most common & treatable eye infection in children & adults.
  • Caused By:virus, bacteria, irritating substances (pool chlorine), allergens, or STD’s.
  • Bolded are the ones that can be spread easily from person to person.
conjunctivitis pinkeye1
Conjunctivitis (Pinkeye)
  • Symptoms:
    • Redness in the white of the eye
    • Increased amount of tears
    • Itchy & burning eyes
    • Blurred vision
    • Yellow, green, or white discharge from the eyes.
  • A group of eye diseases.
  • Categories: closed-angle(acute), open-angle(chronic), & congenital glaucoma.
  • Occurs when the aqueous humor is blocked & drains too slowly from the anterior chamber.
  • Causing a buildup of intraocular pressure.
  • If diagnosed early, blindness can be prevented.
factors that predispose you to glaucoma
Factors that predispose you to glaucoma
  • Age of 60 years or more
  • African ancestry
  • Previous eye injury
  • Use of steroid medication
  • Diabetes
macular degeneration
Macular Degeneration
  • Incurable eye disease
  • Affects more than 10 million Americans.
  • Leading cause of blindness.
  • Caused by: deterioration of the central portion of the retina.
  • Dry: Formation of yellow deposits under the macula.
    • Causing thinning & drying out of the macula.
    • 90% of cases.
    • No known treatment or cure.
macular degeneration1
Macular Degeneration
  • Wet: Abnormal blood vessels grow under the retina & macula.
    • Vessels bleed or leak fluid, causing the macula to lift up.
    • 10% of cases.
    • To save vision, laser surgery needs to be done immediately
  • Dry:
    • Printed words appear blurry
    • Colors that seem washed out or dull
    • Haziness of overall vision that increases
    • Profound drop in central vision
  • Wet:
    • Visual distortions (straight lines appear wavy)
    • Decreased central vision
    • Central blurry spot
color blindness
Color Blindness
  • The inability to see certain colors in the usual way.
  • Occurs when there is a problem with the color-sensing pigments in the eye.
  • If just one pigment is missing, you may have trouble seeing the difference in red & green.
  • Most severe form is achromatopsia.
    • Patient can’t see any color, only shades of gray.
color blindness1
Color Blindness
  • Most is caused by a genetic problem.
  • 1 in 10 men have a form of color blindness.
  • Very few women are color blind.
  • A parent might notice signs of color blindness, when the child is learning their colors.
  • Rice, J. (2008). Medical terminology: A word building approach. (6 ed.). Upper Saddle River, NJ: Pearson Education, Inc.
  • Miller, K., & Levine, J. (2002). Prentice hall biology. Upper Saddle River, NJ: Pearson Education, Inc.